here are the numbers
#1 240
#2 240
#3 245
#4 250

what is the factory compression of a US spec B18C1 per Cylinder
the numbers have been the same since I put my turbo on 4 months ago
I know thats at least good,
let me know what you think.

 

Excellent compression numbers.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GraphiteAccord &raquo;</TD></TR><TR><TD CLASS="quote">Excellent compression numbers.</TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GraphiteAccord &raquo;</TD></TR><TR><TD CLASS="quote">Excellent compression numbers.</TD></TR></TABLE>

damn those are high do you have a milled head??

 

Those are really high for a gsr!!!!!

 

This could be just a stupid question but I heard that carbon buildups on the top on the pistons could result in higher compression when doing a compression test.

How do you guys know if those results are not from the carbon buildups.

 

you could do the sea foam treatment and then you would know you dont have any carbon. lol just look behind you

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Hammett &raquo;</TD></TR><TR><TD CLASS="quote">This could be just a stupid question but I heard that carbon buildups on the top on the pistons could result in higher compression when doing a compression test.

How do you guys know if those results are not from the carbon buildups. </TD></TR></TABLE>

It will raise compression slightly PERIOD, because the carbon buildup is taking up volume in the piston chamber.

But those numbers do seem high.

 

is there any way to get rid of the carbon build up on the pistons without taking off the head?

 

damn... my friends JRSC B18c1 ranges from 225-235psi

 

not stealing your tread but when i first turbo'd my ls, my compression was 150~155 all the way across....after this last weekend's track session...my compression jumped to 180 all the way across. i'm assuming it may either be carbon build up or the fact that i'm using thicker oil(15w-40). either way, i'm a happy camper.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by shermanyang &raquo;</TD></TR><TR><TD CLASS="quote">not stealing your tread but when i first turbo'd my ls, my compression was 150~155 all the way across....after this last weekend's track session...my compression jumped to 180 all the way across. i'm assuming it may either be carbon build up or the fact that i'm using thicker oil(15w-40). either way, i'm a happy camper. </TD></TR></TABLE>

make sure you did the comp. test right,
take off the intercooler line to the TB and make sure you remove all spark plugs to do the test.

 

those number a freaken crazy high. I would only asume that you did that test on a stock motor when it was still very hot or either you have 12+cr or a really milled head.

normally on a warm or even cold motor it should read 175 to 205psi max
what your mainly looking for is if there is a huge difference from each of the cyclinders. even though the numbers are high it looks to be consistant all across.

 

b18c1 came show higher then 205psi max in one cyclinder

 

carbon buildup, hes probably running super rich.

 

thats good numbers

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TraKtioN &raquo;</TD></TR><TR><TD CLASS="quote">carbon buildup, hes probably running super rich.</TD></TR></TABLE>

Carbon buildup wouldnt make the result that high. Did you do the test right??? Are you sure your head isnt milled?

 

dont forget it could be an innacurate guage, also.

 

Smells fishy.. I would retest with a diff gague..

 

he could be spraying gas too, gotta pull the puel pump fuse.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DOHCarp &raquo;</TD></TR><TR><TD CLASS="quote">

make sure you did the comp. test right,
take off the intercooler line to the TB and make sure you remove all spark plugs to do the test.
</TD></TR></TABLE>

ARE YOU SERIOUS!! I have to take off the piping before the TB?!!?!?! how come no one has ever mentioned this before?? i've always left it on, full throttle, all spark plugs out, ecu fuse out...and crank. will leaving the piping on affect anything???

 

full throttle on, leave IC pipes, and pull one spark plug per test, that is how i've always seen, and how i do it.....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by lazerus &raquo;</TD></TR><TR><TD CLASS="quote">full throttle on, leave IC pipes, and pull one spark plug per test, that is how i've always seen, and how i do it.....</TD></TR></TABLE>

Me too with accurate results

 

well since no one is going to let you know this is what it reads for the b18c1/5

Standard 270psi
Minimum 135psi
Max diff. between any two is 28psi....

Your reading are normal......not high...

 

270psi if you have 12.5:1cr pistons!